Rotary compressor



Feb. 8, 1927. 1,616,992

A. RUCKSTUHL ROTARY COMPRFIS SOR Filed Dec. 11. 1925 Patented Feb. 8, 1927.

UNITED STATES PATENT OFFICE.

ALWIN QBUCKSTUHL, OF WINTEBTHUR, SWITZERLAND.

ROTARY COMPRESSOR.

Applicationfiled'necember 11, 1925, Serial No. 74.825, and in Germany may], 1925.

It is known from experience that with the usual control of rotary compressors provided with stationary distributing channels which only permits a closing of the suction branch and a simultaneous connection of the delivery branch to the surrounding atmosphere very violent and sudden changes in the power absorbed by the compressor occur, which may cause disagreeable troubles in the plants supplying the driving power and may even cause a complete standstill of such plants in case they are comparatively weak. The use of devices efiecting a retardation of the movements of the controlling organs does not improve these conditions as the sudden change of load depends on the simultaneous closing of the suction branch and the opening of the delivery branch.

According to the present invention a division of the controlling effect into two phases is contemplated inasmuch as at first the delivery branch is slowly connected to the surrounding atmosphere and the suction branch is slowly closed only after a predetermined pressure is reached in the delivery branch.

A constructional example of a device for carrying into effect this method of controlling a rotary compressor is diagrammatically illustrated on the accompanying drawings, in which:

Fig. 1 is a vertical section of the rotary engine and the controlling gear,

Figs. 2 and 3 show details of the controlling gear in different operative positions.

As is shown in Fig. 1 the rotary compressor is in its normal design provided with a casing 1 in which the drum or rotor 2 containing the gates 3 is ecccntrically mounted. The air enters the compressor through the suction branch S and leaves it through the p delivery branch or pressure branch D. In the latter a non-return valve 4 1s arranged which prevents the compressed air in the con- -a control relay 7 by duit 5 from flowing back into the compressor when the controlling action'has started. The pressure conduit. 5 is further connected to means of conduit 6, which relay comprises two. small distributing pistons 8 and 9 which may be acted upon by springs or weights and which permit the controlling action to take efiect only after a determined pressure in the pressure conduit has been reached. The relay 7 is then connected by the conduit 12 to a receptacle 14 containing a viscous liquid. The latter may I flow through the pipe 15- to act on the piston are provided on the lever 17 r'or the purpose of adjusting the moment in which the lever acts upon the valve 18 and the shut-off valve 22. "The return movement of the overflow valve 18 is caused by the spring 25 and that of the shut-01f valve 22 by the spring 26. The shut-0E valve 22 is provided with ports 27 which register with corresponding ports 28 in the casing 21 when the valve 22 is in its uppermost position, in which case the air which is sucked through the suction conduit 29 is permitted to flow to the suction branch S. The casing 20 of the overflow valve 18 is connected on one side to the pressure branch D by the conduit 30 and on the other side to the surrounding atmosphere by means of the pipe 31.

If the desired highest pressure is reached the weights corresponding to this pressure are lifted by the air acting on the piston 8 whereby the conduit Sand the channel 10 are connected with each other. The air nowgets below the distribution piston 9 and lifts the latter and uncovers thereby the pressure equalizing channel 11 and connects the conduits 6 and 12 with each other. The air flows now through the conduit 12 above the liquid level in the casing 14. The

controlling means take up the position illustrated in Fig. 2. The compressed air forces the liquid through the pipe 15 to act on the piston 16 from below. The velocity of the liquid flowing through the pipe 15 may be regulated by adjusting the set screw 32 which ermits the liquid flow to be throttled and thereby adjust the duration of the controlling action to the intermediary of the liquid on the lower side of the piston 16 lifts the latter and thereb turns the lever 17. The set screws 23 an 24 are so adjusted that at first the overflow valve 18 is opened and a connection between the pressure branch D and the any requirement. The pressure exerted by the compressed air through mum does the distri 40 escapes throu delivery branch to be lowered and the nonreturn valve to close automatically. As soon as the pressure in the delivery branch D has been reduced in the desired degree the set screw 24 of the lever 17 presses the shutoff valve 22 in' thedownward direction. In consequence thereof the ports- 27 are displaced relative to-the ports 28 and in the lowermost position of the valve these ports are altogether whereby the suction conduit 29 is separated from the suction branch S and the machine runs as a vacuum pump. The closing of the entrance ports to the suction branch has also to be performed slowly and in a determined manner which is taken into account bythe shape of the valve ports 27.

The sequence of the above described movements is reversed when the compressor has to start again; When the pressure in the conduit 5 is lowered by a fraction of one atmosphere the raised distributing piston 8 moves in the downward direction by the influence of the weight wherebythe connection between the conduit 6 and the channel 10 is interrupted as is shown in Fig. 3.

is movement, however, does not cause a simultaneous movement of the piston 16, as the pressure below the distribution piston 9 is maintained by the flow of air through the pressure equalizing channel 11. Only when the pressure has dro ped to'the desired miniution piston 9 which is loaded by a corresponding weight return by the action of said weight into its lowermost position and close the pressure equalizing channel 11 and connect the conduits 12 and 13 with each other. The compressed air present above the liquid in the receptacle 14 gh the conduits 12 and 13 into the surrounding atmosphere and suspends the pressure below the piston 16. The spring 26 of the shut-off valve 22 and the spring 25 of the overflow valve 18 are then operative and return these parts into their initial positions, whereby the liquid below the piston 16 recedes only slowly on account of the throttling organ 32. Thereafter first of all the shut-01f valve 22 and the suction conduit are opened and the compressor is loaded 'thereb later on the overflow valve 18 closes the overflow opening and the com pressor is again ready for normal working (all the parts being again in the position.

shown in Fig. 1).

I claim: a 1. Mechanism for controlling a rotary compressor comprising in combination,

means to connect the delivery of the compressor to the surrounding atmosphere, means to interruptthe suction action, and

a. pmsure responsive device operatively connected to both of said means and causing the st mentioned means to be. operative before 0 the second ,mentioned means to obtain a separated from each other v I gradual reduction in the powerabsorbed in driving the compressor, and vice versa to obtain a gradual increase in said power, said a fluid distributing system connected to the delivery branch and to said device, and loaded distributing pistons controlling said system whereby said pressure responsive device actuates'said means and said cut-01f organ when a determined pressure in the delivery branch which corresponds to the load on the distributing pistons is reached.

3. An arrangement for controlling a rotary compressor having a suction branch and a delivery branch, comprising in combination, a non-return valve cooperating with the delivery branch, a cut-off organ cooperating with the suction branch, means adapted to connect the delivery branch to the surrounding atmosphere, a valve interposed in said means, a pressure responsive device ineluding a receptacle containing a liquid and p a piston displaceable by said liquid to cooperate with said cut-off organ and with said valve, a fluid distributing system connected to the delivery branch and to said device, and two loaded distributing pistons. controlling the flow of fluid in said system'whereby said pressure responsive device actuates said valve and said cut-ofl' organ when a determined pressure in the delivery branch which corresponds to the load on the distributing pistons is reached.

n arrangement for controlling a rotary compressor having a suction branch and a delivery branch, comprising in combination, a non-return valve cooperating with the delivery branch, a cut-off organ cooperating with the suction branch, means to connect the delivery branch to the surrounding atmosphere, avalve interposed in said means, a pressure responsive device including a receptacle containing a liquid, a piston displace'able by said liquid and a three armed lever to cooperate with said piston, said cut-ofl' organ cylinders one of which being" connected to the delivery branch and the otherbeing connected to the receptacle of said pressure responsive device, a plurality of interconnections between said cylinders, and two loaded distributing pistons for controlling said connections and thereby the flow of. fluid he ya d P e s e re p nsive device and said valve, two relay tuates said valve and said cutofi' organ when a determined pressure in the delivery branch which corresponds to the load on the distributing pistons is reached.

-5. An arrangement for controlling a rotary compressor having a suction branch and a delivery branch, comprising in combination, a non-return valve cooperating with the delivery branch, a cut-off organ cooperating with the suction .branch,means to connect the delivery branch to the surrounding atmosphere, a valve interposed in said means, a pressure responsive device in-' cluding a receptacle containing a liquid, a

piston displaceable by said liquid, a three armed lever to cooperate with said piston, said cut-oil organ and said valve, adjustable name to this specification.

means on said three-armed lever to time the cooperation of said lever with said cut-off organ and said valve, and throttling means for adjusting the action of the liquid on said piston, two relay 0 linders one of which is connected to the delivery branch and the other connected to the receptacle of said pressure responsive device, a plurality of interconnections between said cylinders, and two loaded distributing pistons for controlling the flow of fluid through said connections when a determined pressure in the delivery branch which corresponds to the load on the distributin istons is reached.

In testimony whereoi have signedmy ALWIN RUCKSTUHL. 

